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Li R.,State Radio Monitoring Center | Li J.,State Radio Monitoring Center Testing Center
2014 31th URSI General Assembly and Scientific Symposium, URSI GASS 2014 | Year: 2014

Based on statistical delay quality of service (QoS) constraints, effective capacity in underlay cooperative cognitive radio network is investigated. Distinct from other researches, the cooperative transmission takes both direct link and relay link of secondary user into account. The secondary receiver merges the signals from the two links to obtain diversity gain and transmission reliability. Under the statistical delay QoS constraints, the paper obtains the maximum arrival-rate supported by the secondary user's cooperative links, and derives a closed-form expression of effective capacity. Finally, simulations are made to verify the performance of theoretical analysis. © 2014 IEEE. Source

Zhu H.,Beijing University of Posts and Telecommunications | Peng X.,State Radio Monitoring Center Testing Center | Sun X.,Beijing University of Posts and Telecommunications | Zhou Z.,Beijing University of Posts and Telecommunications
Lecture Notes in Electrical Engineering | Year: 2012

In this chapter, we investigated a promising physical layer network coding-based two-way relay technique for the emerging 60 GHz millimeter-wave wireless personal area networks (WPANs), in order to address the problem of throughput reduction in relay nodes caused by the blockage of links. Because of the small wavelength at 60 GHz frequency band, links may be seriously blocked by the involved obstacles such as furniture and humans. The key idea of the most common solution to handle blockage proposed by now is to substitute the two line-of-sight (LOS) links for the blocked link. However, this method reduces the throughput of the network by a factor of two, which may hence fail to provide the required QoS guarantees to realistic WPAN applications. Our suggested new approach introduces a two-way relay scheme using physical layer network coding to the 60 GHz millimeter-wave WPANs, which can accomplish information exchange within two time slots instead of four. Simulation results, such as bit error rate and throughput, demonstrate the effectiveness of the proposed two-way relay scheme in 60 GHz WPANs. © 2012 Springer Science+Business. Source

Li S.,Beijing University of Posts and Telecommunications | Tao H.,State Radio Monitoring Center Testing Center | Zhao C.,Beijing University of Posts and Telecommunications
Lecture Notes in Electrical Engineering | Year: 2012

60 GHz Wireless Communication has attracted increasing attention with its distinct advantages such as abundant bandwidth, unlicensed and so on. For overcoming the large path loss of 60 GHz spectrum, devices generally make use of antenna array to get high directivity beam, enhance transmit and receive antenna gain. As a result how to implement fast beam-search is an inevitable challenge for 60 GHz Wireless Communication. Based on IEEE 802.15.3C criteria and channel model(including application environments), this chapter aims to propose a novel beam-search strategy by taking into account the characteristics of 60 GHz Wireless Communication, such as large path loss, strong directional beam and correlation among beam-search of devices. Moreover this strategy was proved by the simulation that it can effectively reduce the range of beam-search, improve efficiency. © 2012 Springer Science+Business. Source

Luo L.,China Electric Power Research Institute | Zhou J.,China Electric Power Research Institute | Ling P.,China Electric Power Research Institute | Roy S.,University of Washington | And 2 more authors.
International Journal of Distributed Sensor Networks | Year: 2015

Cognitive radio sensor networks (CRSN) have the potential to vastly improve spectrum utilization among heterogeneous applications for smart grid. To date, there has been little queueing theoretic modeling conducted of such systems that provide a quantitative estimate of the benefits from CRSN. We propose a novel queuing model which incorporates service rate and functional heterogeneity on the servers and implement preemptive priority among the varying service classes. Initially, we present a continuous-time Markov chain for performance analysis of CRSN for two colocated cognitive systems with various priority classes and bandwidth requirements. Closed form results for spectrum utilization, blocking probability, and optimal traffic intensities are then derived for the scenario of two heterogeneous secondary systems. A channel packing scheme is then proposed to pack smaller bandwidth users into clusters of adjacent channels to alleviate blockage of users requiring larger bandwidth requirements. Based on the numerical results of benefits of our scheme, we propose a feasible application for smart grid. © 2015 Ling Luo et al. Source

Li B.,Beijing University of Posts and Telecommunications | Sun M.,Beijing University of Posts and Telecommunications | Li X.,State Radio Monitoring Center Testing Center | Nallanathan A.,Kings College London | Zhao C.,Beijing University of Posts and Telecommunications
IEEE Transactions on Signal Processing | Year: 2014

Cognitive radios may operate in practice under various adverse environments. For typical mobile and short-range scenarios, wireless links may tend to be time and frequency selective, i.e., the multipath propagations with time-varying fading coefficients will be inevitable. To cope with the encountered doubly-selective channels, in this paper we present a new spectrum sensing algorithm for distributed applications. First, a dynamic discrete state-space model is established to characterize sensing process, where the occupancy state of primary band and the time-varying multipath channel are treated as two hidden states, while the summed energy is adopted as the observed output. With this new paradigm, spectrum sensing is realized by acquiring primary states and time-dependent multipath channel jointly. For the formulated problem, unfortunately, Bayesian statistical inference may be impractical due to the absence of likelihoods and involved non-stationary distributions. To remedy this problem, an iterative algorithm is further designed by resorting to sequential importance sampling techniques; thus, the dynamic non-Gaussian multipath channel and primary states are estimated recursively. Another critical challenge, e.g., the noise uncertainty, is also considered, which may be incorporated conveniently into this sensing diagram and, furthermore, addressed effectively by the designed algorithm. Simulations validate the proposed algorithm. While classical schemes fail to deal with doubly selective channels, the new sensing scheme can exploit the underlying channel memory and operate well, which provides a great promise to realistic applications. © 2014 IEEE. Source

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